The subject is further complicated by the high prevalence of prostate cancer detected at autopsy [7], the high frequency of positive prostate biopsies in men with a normal digital rectal examination (DRE) and PSA <4.0 ng/mL [8], the contrast between the incidence and mortality rates for prostate cancer, and the need to treat an estimated 37 men with screened detected prostate cancer to prevent one prostate cancer death [9, 10]. Here, KLK3 is linked to prostate cancer.